Bis-trihydrocarbon silylphenyl silanes



Patented May 16. 1950 BIS-TRIHYDROCARBON SILYLPHENYL SILANES Harold AfClark, Midland, Mich., assignor to Dow .iLGOrning Corporation, Midland, Mich, a corpo- --ration of Michigan -NoDrawing. Application February 23i'1949,

. Serial No. 77,990

This invention relates to organo s'ilane poly- In the applicant's copending application, filed concurrently herewith and assigned to the Dow Corning Corporation compounds of the type RsSiRSiRa were disclosed and claimed. The present invention deals with compounds having two R. groups per molecule.

It is an object of this invention to prepare compounds which are useful as vacuum diffusion pump fluids, lubricants and constant temperature baths. Other objects and advantages will be apparent from the following description.

This invention relates to compounds of the type where each R is a phenyl or methyl radical.

The compounds of this invention may be prepared by condensing a chlorinated tetraorgano silane of the type R3SiCsH4Cl with a dichlorosilane of the type RzSiClz. The condensation may be carried either by means of the Grignard reagent or by a Wurtz reaction. The latter is a preferred method.

More specifically a mixture of the dichlorosilane and the tetrasilane may be reacted with an alkali metal such as sodium, potassium or lithium in a toluene solution. Condensation takes place to produce a trimeric silphenane with the concurrent splitting out of alkali metal chloride. The latter is then filtered and the solvent removed at reduced pressure.

The compounds of this invention are liquids of varying viseosities. They are characterized by extreme thermal stability and high oxidation resistance. The compounds may be heated indefinitely at 350 C. in the absence of oxygen without undergoing thermal rearrangement. In the presence of oxygen they may be heated indefinitely at 150 C. and for limited periods of time at temperatures up to 250 C. without showing any decomposition. In addition the materials are extremely stable to alkali and acid reagents. This is in contrast with the corresponding siloxanes which are rearranged by such reagents.

The above combination of properties makes the present compounds useful for many applications. V

These include use as lubricants, vacuum diffusion pump fluids and as the liquid medium for constant temperature baths.

In order that those skilled in the art may better understand this invention, recourse may be 2 had to the following examples which should be considered as illustrative only.

EXAMPLES Example 1 97.9 g. of chlorophenyltrimethylsilane was mixed with 50.6 g. of ph'enylmethyldichlorosilane in 200 cc. of toluene. The toluene solution was added to 2'? g. of molten sodium in 500 cc. of refiuxing toluene. The reaction was exothermic so that reflux of the solvent was maintained by regulating the rate of addition of the reactants. After three hours the reaction was complete and the mixture was filtered and toluene was removed at reduced pressure. The residue was a clear oil having a viscosity of 4120 cs. at C. This material was This compound has a boiling point of 194 to 201 C. at 0.5 mm., a freezing point of 4 C. and a refractive index of 15604 at 25 C. The compound was placed in a single stage diffusion pump and operated at 194 C. with a fore pressure of microns. A pressure of 1.7x 10- was obtained in less than 25 minutes after the oil began to boil.

Example 2 The compound CH3 (CHQaSlCeHAiCeESKCHs)a was prepared according to the method of Example 1 by reacting 200 g. of chlorophenyltrimethylsilane with g. of dimethyldichlorosilane and 54 g. of molten sodium. The compound is an oil having a viscosity of 28.6 cs. at 25 C. and a boiling point of 142 C. at 25 mm.

Example 3 The compound CoHn (CHQaSiCuHAiCuHfiKCHa)a was prepared according to the method of Example 1 by reacting 125.9 g. of chlorophenyltrimethylsilane, 85.7 g. of diphenyldichlorosilane and 34.3 g. of molten sodium. The compound is a viscous material boiling at 205 to 215 C. at 0.3 mm.

That which is claimed is:

1. A compound having the formula where each R is selected from the group consisting of phenyl and methyl radicals.

Cells CH: (C HzhSiOuHAiOgEhBi (0 H4);

5 (CH3) :SiCaHAiCa ASi (0 H1):

5. The process for producing compounds of the type a msiodzlmmsm,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Rochow July 4, 1944 OTHER. REFERENCES Goodwin: Jour. Am. Chem. 600.," vol. 69 (1947). page 2247.

Summer: Jour. Am. Chem. 800., vol. 69 (1947) page 980.

Bluestein: Jour. Am. Chem. $00.," vol. 69 (1947), pages 3068-71.

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1. A COMPOUND HAVING THE FORMULA 